Cisco ASR1001

I'm looking for experiences with Cisco ASR1001 as a border router,
specifically BGP stability, # full BGP feeds (with 4 GB DRAM), does it
perform according to wire speed acl/firewall/deep packet inspection


Wire speed? You propably misread the data sheet. Look at table 1:

The QFP will perform ACLs/DPI very fast, but not at wire speed for
commonly used edge ACLs. There will be slight performance hit depending
on the lenght of the ACLs and the complexity of the inspection.

Also take note half of the theoretical RAM is reserved on start, so
you end up running your system with 1GB of usable RAM, other 1GB taken
during the start by the IOS-XE. For a lot of BGP peerings you should
get at least 8GB to be on the safe side, but the default, cheapest 4GB
will work fine with small number of full feeds.

Also take note that this is hardware forwarding platform, so FIB size
will come into play - not now, but given IPv6 growth, in future.
ASR1001 has FIB for 1M of IPv4 *or* 1M of IPv6 prefixes, you'll need
to check that from time to time (QFP memory usage that is).